Recently, batteries having a small size, a light weight, a long life and a high energy density are particularly demanded with the rapid advance of electronics as a power source for small-size electronic equipments. In this connection, non-aqueous electrolyte primary batteries such as a lithium primary battery using manganese dioxide as a positive electrode and lithium as a negative electrode and the like are known as one of batteries having a high energy density because an electrode potential of lithium is lowest among metals and an electric capacity per unit volume is large, and many kinds thereof are actively studies. On the other hand, there are developed run-flat tires capable of continuously running up to a repairing service place over a significant distance even if puncture or the like is caused in a pneumatic tire. Based on this, it is proposed to arrange on the run-flat tire an internal pressure alarm device which measures a tire internal pressure and transmits an accident-informing signal when the internal pressure is dropped to not more than a constant value. As a power source for the internal pressure alarm device is used the non-aqueous electrolyte primary battery having a small size, a light weight, a long life and a high energy density and using manganese dioxide as a positive electrode and lithium as a negative electrode.
In the above non-aqueous electrolyte primary battery, lithium is frequently used as a material forming the negative electrode. However, since lithium violently reacts with a compound having an active proton such as water or alcohol, an electrolyte to be used is limited to a non-aqueous solution or a solid electrolyte. Since the solid electrolyte is low in the ion conductivity, it is limited only to the use at a low discharge current. Therefore, the electrolyte usually used at the present time is an aprotic organic solvent such as ester based organic solvent or the like.
On the other hand, nickel-cadmium batteries were particularly the main current as a secondary cell for backing up memories in AV-information equipments such as personal computers, VTR and the like or a power source for driving them. Recently, non-aqueous electrolyte secondary batteries are considerably noticed instead of the nickel-cadmium battery because they are high in the voltage and have a high energy density and develop an excellent self-discharge characteristic, and hence various developments are attempted and a part thereof is commercialized. For example, a greater number of note-type personal computers, mobile phones and so on are driven by such a non-aqueous electrolyte secondary battery.
In the non-aqueous electrolyte secondary battery, since lithium-containing composite oxide is used as a material forming a positive electrode and carbon is frequently used as a material forming a negative electrode, various organic solvents are used as an electrolyte for the purpose of reducing a risk when lithium is formed on the surface and rendering a driving voltage into a higher level. Also, an alkali metal or the like (particularly, lithium metal or lithium alloy) is used as a negative electrode in the non-aqueous electrolyte secondary battery for a camera, so that an aprotic organic solvent such as ester type organic solvent or the like is usually used as an electrolyte.